Salt hydrate-bf3-hgx2 catalyst



3,024,204 SALT HYDRATE-El -HgX CATALYST Harmon M. Knight, La Marque, and.l'oe T. Kelly, Dickinson, Tex., assignors, by mesne assignments, toStandard Oil Company, Chicago, llll., a corporation of lindiana NoDrawing. Filed Oct. 27, 1953, Ser. No. 769,598

3 Claims. (Cl. 252*433) This invention relates to a catalyst adapted forconversions of hydrocarbons and processes utilizing the catalyst.

An object of the invention is a catalyst of the ferric pyrophosphate-BFtype set out in U.S. 2,824,146, which does not require additional BF Afurther object is a solid catalyst containing ferric pyrophosphatehydrate and BF Other objects will become apparent in the course of thedetailed description of the invention.

It has been discovered that an eifective catalyst for many hydrocarbonreactions, particularly polymerization,

is obtained by intermingling ferric pyrophosphate hydrate- BF complex,as hereinafter defined, and mercuric halide, in a hereinafter definedratio, where the halide is chloride or bromide.

The catalyst composition consists essentially of two solid members. Onemember is a complex having the empirical formula Fe (P O .aH O.bBF Wherea is at least 1 and b isfrom l to a. Ferric pyrophosphate forms hydrateswith Water, which hydrates may contain from 1 to as many as 18 moles ofwater of hydration per mole of ferric pyrophosphate. In general, it ispreferred that the complex be formed from ferric pyrophosphate hydratecontaining from 6 to 9 moles of water of hydration per mole of ferricpyrophosphate. Boron trifluoride must be present in the complex;apparently the BP complexes with the hydrated water to form a solidmaterial. in order to attain effective catalytic activity, it isnecessary that the complex contain at least 1 mole of BF per mole of thehydrate, and preferably the complex should contain 1 mole of BF for eachmole of water of hydration present. To illustrate, when ferricpyrophosphate.6H O is the hydrate, the complex must contain at least 1mole of BF and preferably contains 6 moles of BF}; these two complexesmay be written as Fe (P O .6I-l O.BF and Fe. ,(P O .6H O.6BF

The BF and the hydrate are reacted to form a solid material containingcomplexed BF When the salt hydrate and BF are contacted in a closedvessel, the B1 partial pressure drops very rapidly at first and thengradually approaches a constant value. It appears that a very rapidreaction between the BF and some of the water of hydration takes place.This initially rapid reaction is then followed by a relatively slowreaction between the remaining molecules of hydrate Water and additional3P In the case of ferric pyrophosphate containing 11 moles of hydratewater per mole of the salt, it appears that 4 or moles of hydrate waterare rapidly reacted. However, stirring of finely powdered hydrate saltin the presence of excess BF at about room temperature for a period ofabout hours, results in the reaction of l'mole of BP for each mole ofhydrate water present in the ferric pyrophosphate hydrate.

The solid complex of ferric pyrophosphate hydrate and BE, has moderatecatalytic activity and may be used for purposes such as polymerizingisobutylene. This cornplex has no activity for the difiicultethylene-isobutane alkylation reaction or ethylene polymerization. Ithas been found that a catalyst system of very great polymerizationactivity is obtained by intermingling the defined ferric pyrophosphatehydrate-BF complex with mercuric chloride or mercuric bromide in aweight ratio of ferric pyrophosphate to HgX- from about 1 to about 75.The com- 3,024,204 i atented Mar. 6, 1962 position consistingessentially of the defined complex and HgXg in this ratio is veryeffective for promoting the difiicult ethylene polymerization reaction.The bromide containing catalyst is preferred for ethylene-isobutanealkylation.

The defined composition of complex and HgX may be used as such; thecomposition may be used in the form of a powder or shaped into pellets.Or, the catalyst composition may be supported on a carrier such asalumina, pumice, silica, silica alumina and carbon.

The catalyst may be used at any temperature below the temperature atwhich the salt hydrate decomposes, that is, loss of all its water ofhydration. The temperature of operation may be as low as -25 C. or evenlower. Temperatures as high as 150 C. and even higher may be used withsome of the hydrates which have rela tively high decompositiontemperatures. For example, ferric pyro hosphateSH O has been heated for20 hours at 168 C. Without losing water of hydration. More usually thetemperature of operation will be below about 30 C. Low temperaturesfavor the formation of the hydrocarbons having 6 to 7 carbon atoms anddiisopropyl in ethylene-isobutane reaction. It is preferred to operatethis alkylation process at a temperature between about 25 C. and -l5 C.

Sufiicient pressure is maintained on the system to keep a substantialportion of the hydrocarbons charged in the liquid state. In general,pressures will be between about 50 and 1000 psi. and preferably betweenabout and 600 p.s.i. for alkylation or polymerization.

The reactants in the hydrocarbon charge to the alkylation process areisoparaffin, or aromatic and olefin. The olefin contain from 2 to about12 carbon atoms. Examples of suitable olefins are ethylene, propylene,butene- 2, hexene and octene; in addition to these, the olefin polymersobtained from propylene and/or butylene are also suitable for use in theprocess, such as codimer, propylene trimer, propylene tetramer andbutylene trimer. It is preferred to operate with ethylene or propylene.

The aromatic hydrocarbons must be alkylatable by the particular olefinused. It is self-evident that an aromatic hydrocarbon which containsalkyl substituents positioned so that steric hindrance would prevent orgreatly reduce the possibility of alkylation with the particular olefinshould not be subjected to the process. Examples of particularlysuitable aromatic hydrocarbons are benzene, toluene, xylene,trimethylbenzenes, and the other alkyl analogues, such as propyl andbutyl, the naphthalene aromatic hydrocarbons, such as the mono anddi-substituted methylnaphthalenes.

The isoparafiin reactant is defined as a parafiinic hydrocarbon whichhas a tertiary hydrogen atom, i.e., parafins which have a hydrocarbonatom attached to a tertiary carbon atom. Examples of these areisobutane, isopentane (Z-methylbutane), Z-methylpentane, Z-methylhexane,3-methylhexane, 2,3-dimethylbutane (di-isopropyl) and2,4-dimethylhexane. Thus the isoparaffins usable as one reactant in theprocess contain from 4 to 8 carbon atoms.

In the isoparaflin-olefin system, the alkylation reaction is morefavored as the mole ratio of isoparaffin to olefin increases. Ingeneral, the isoparatfin to olefin mole ratio in the hydrocarbon chargeshould be at least 1. More than this amount is good and it is desirableto have an isoparafrin to olefin ratio between about 2 and 25 and insome cases more, for example, as much as 50. It is preferred to operatewith an isoparaffin to olefin mole ratio of between about 5 and 15.

The presence of non-reactive hydrocarbons in the hydrocarbon charge isnot detrimental unless the reactants become excessively diluted. Forexample, the isoparaffin may also contain isomers of the normalconfiguration. The olefins may contain paratfins of the same carbonnumber. Mixtures of 2 or more isoparaffins or 2 or more aromatichydrocarbons, or 2 or more olefins may be charged. In general, when aparticular product distribution is desired, it is preferable to operatewith a single isoparaffin and a single olefin, for example, technicalgrade isobutane and ethylene, i.e., about 95% purity.

The reactants may be mixed together before they are charged into thereactor. Or, they may be charged into the reactor separately. Or, aportion of the olefin may be blended with the isoparaffin or aromaticbefore introduction into the reactor and the remainder of the olefininjected into the reactor. The charge may be introduced all at one pointinto the reactor or it may be introduced at 2 or more points. Thealkylation reaction is somewhat exothermic and temperature control isfacilitated by introducing the olefin into the reactor at more than onepoint.

The contacting of the isoparaffin or aromatic hydrocarbon and the olefinin the presence of the. defined catalyst pair is continued until anappreciable amount of alkylate has been formed. In batch reactions, itis possible to virtually extinguish the olefin, i.e., convertsubstantially 100% of the olefin by a sufficiently long period ofcontacting. When operating in a continuous flow system, it may bedesirable to have a time of contacting such that substantial amounts ofolefin are not converted and obtain the complete conversion of theolefin by a recycle operation. The time of reaction will be determinedby the type of hydrocarbons charged, the ratio of isoparaffin oraromatic to olefin, the degree of mixing in the contacting zone and thecatalyst usage. A few tests will enable one to determine the optimumtime of contacting for the particular system of operating conditionsbeing tried.

The catalyst system is distinguished by its ability to polymerizeethylene. Other olefins such as propylene, butylene, isobutylene, etc.,are polymerized by the catalyst system of the invention. Even in thepresence of isobutane, the system containing mercuric chloridepreferentially polymerizes ethylene and other olefins. The catalystcontaining mercuric bromide is not as partial to the polymerizationreaction. The polymerization reaction is carried out using the olefin insubstantially the liquid state and otherwise under conditions similar tothose described hereinabove for the alkylation reaction.

The hydrocarbon reaction may be carried out in a reactor which may be avessel providing for a batchtype reaction, i.e., one wherein the desiredamount of isoparatfin or aromatic and olefin are charged to a closedvessel containing the catalyst pair and the vessel then maintained atthe desired temperature for the desired time. At the end of this time,the hydrocarbon product mixture and unreacted materials are withdrawnfrom the vessel and processed to separate the al-kylate product from theunreacted materials and lower and higher molecular weight materials. Thereaction may be carried out in a fixed bed operation wherein thereactants are flowed through a bed of catalyst, the space velocity beingcontrolled so that the desired amount of reaction is obtained during thepassage of the reactants through the bed. Under some conditions, amoving bed of catalyst may be utilized. In still another set ofcircumstances, a fluidized bed may be utilized with the incoming streamof reactants providing the energy for the fiuidization of the catalyst.Other methods of operation .common in the catalytic refining aspects ofthe petroleum industry utilizing solid catalyst may be readily devised.

Tests For purposes of illustration, the results of comparable testsusing a catalyst composition of the invention and the complex alone areset out below.

The tests were made as follows: g. of

F4(P2O7)3.9H2O

and 200 ml. of isobutane were charged to a dry 4-liter carbon steelbomb. The bomb was then placed in an ice bath and cooled. BF was slowlyadded with care to avoid overheating of the salt as a result of theexothermic reaction. The bomb was gradually pressured to 250-300p.s.i.g. with B1 and allowed to stand until the desired amount of BF hadbeen taken up, after which the bomb was depressured and evacuated. TheHgX (when used) was added and then 1000 g. of a blend of isobutane andethylene were charged (3/1 molar U0). The bomb was rocked 20 hours at15- 25 C. and then sampled for Podbielniak distillation analysis.

Test 1.Only 18 weight percent of alkylate were obtained when only theferric pyrophosphate.9I-l O.9BF complex was present in the reactor. Thiscompares with an alkylate yield of about 30% when 8P alone is used as acatalyst in this same system.

Test 2.-In this test, mercuric bromide was used in conjunction withferric pyrophosphate.9H O. Sufficient BF; was present in the complex tohave a molar ratio of B1 to hydrate water of 0.8. The mercuric bromidewas present in the reactor in an amount such that the ferricpyrophosphate to mercuric bromide weight ratio was 2.2. In this test allthe ethylene reacted. The yield of total all-:ylate, based on ethylenecharged was 178 weight percent; the product fractions consisted ofisopentane, 12%, hexanes, 30%, octanes, 56% and nonanes and higher, 76%.The hexanes and octanes had essentially 0 bromine number; the nonaneplus fraction had a bromine number of 17.

Test 3.In this test, two runs were carried out at conditions identicalexcept for the weight ratio of ferric pyrophosphate to mercuricchloride. Ferric pyrophosphate.- 9H O and BE were charged to the reactorto obtain a complex containing 0.8 mole of BF per mole of hydrate water.In run 3a, the weight ratio of ferric pyrophosphate to mercuric chloridewas 2.2. The total yield of product, based on ethylene chargedall ofwhich was reactedwas 143 weight percent. The product consisted ofisopentane, 8%, hexanes, 16%, and higher boiling materials, 119%. Thehigher boiling product had a bromine number of 34.

In Test 3b, the weight ratio of ferric pyrophosphate to mercuricchloride was 18.0. In this test, all of the ethylene charged wasreacted. The yield of product based on ethylene charged was 117 weightpercent, i.e., very little reaction other than polymerization tookplace. The product consisted of isopentane, 77%, hexanes, 13%, andhigher boiling materials, 97%. The higher boiling material had a brominenumber of 19.

Test 4.In this test, ferric pyrophosphate.6H O and BF were complexed toobtain a solid material containing 0.3 mole of BF per mole of hydratewater. The weight ratio of ferric pyrophosphate in this test to mercuricchloride was 2.2. The total yield of product was 114 based on ethylenecharged-all of which was reacted. 'I he product consisted of isopentane,4%, hexanes, 7%, and higher boiling materials, 103%. The higher boilingmaterial had a bromine number of 10.

Thus having described the invention, what is claimed 1. A compositionconsisting essentially of (1) a complex having the empirical formula Fe(P O .aH O.bBF where a is at least 1 and b is from 1 to a and (2) HgXwhere X is from the class consisting of chloride and bromide and wherethe weight ratio of said pyrophosphate to said halide is from about 1 toabout 75.

2. A composition consisting essentially of (1) the complex Fe (P O .9I-IO.9BF and (2) HgCl where the weight ratio of said pyrophosphate to saidchloride is about 25.

5 3. A composition consisting essentially of (1) the complex Fe (P O-;).9H O.9BF and (2) HgBr where the Weight ratio of said pyrophosphate tosaid bromide is about 2-5.

References Cited in the file of this patent UNITED STATES PATENTS2,471,130 Vesterday May 24, 1949 6 Watkins May 29, 1956 Field et a1.Dec. 4, 1956 Kelly et a1 Feb. 18, 1958 Breslow Mar. 18, 1958 ShiifierSept. 9, 1958 Fotis et a1 Sept. 16, 1958 Starcher Dec. 9, 1958

1. A COMPOSITION CONSISTING ESSENTIALLY OF (1) A COMPLEX HAVING THEEMPORICAL FORMULA FE4NP2O7)3.AH2O.BBF3 WHERE "A" IS AT LEAST 1 AND "B"IS FROM 1 TO "A" AND (2) HGX2 WHERE XIS FROM THE CLASS CONSISTING OFCHLORIDE AND BROMIDE AND WHERE THE WEIGHT RATIO OF SAID PYROPHOSPHATE TOSAID HALIDE IS FROM ABOUT 1 TO ABOUT 75.